Normally deenergized coded signaling system



Oct. 24, 1944. A. JEROME 2,360,948

NORMALLY DEENERGIZED CODED SIGNALING SYSTEM 4 Sheets-Sheet 1 Filed Dec. 7, 1943 INVENTOR APLbaPL. Jerome gg/liwea H15 ATTORNEY 'Oct. 24, 1944. A. 1.. JEROME NORMALLY DEENERGIZED CODED SIGNALING SYSTEM Filed Dec. 7, 1943 4 Sheets-Sheet 2 IN VENTOR Ape 125mb. Jerome.

Hi5 ATTORN EY Patented Oct. 24, 1944 UNlTED STATES NORMALLY DEENERGIZED CODED SIGNALING SYSTEM Arthur L. Jerome, Edgewood, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 7, 1943, Serial No. 513,229

19 Claims.

My invention relates to an improved railway signaling system whichoperates without line wires and is arranged so that the apparatus for each track section is normally deenergized and becomes energized on the approach of a train and becomes deenergized on passage of a train through the track section.

It is an object of this invention to provide an improved system of the type described which operates to provide a two-block three-indication signaling system.

Another object of the invention is to provide a system of the type described which is arranged so that the lamps of the wayside signals are normally extinguished and become lighted only when the adjacent section in the rear is occupied.

A further object of the invention is to provide a system of the type described which is arranged so that appropriate signal indications will be provided for the second of two trains regardless of how closely it follows the first train.

Another object of the invention is to provide a system of the type described which may be employed in track stretches through which are operated locomotives equipped with cab signal apparatus responsive to flow of coded alternating current in the track rails.

I shall describe two forms of normally deenergized ceded signaling system embodying my invention, together with a modification thereof which I may employ, and shall then point out the novel features thereof in claims.

In practicing my invention, I supply to the rails of the adjacent section in advance of a train at the entrance end of the section master code ofone polarity. This operates equipment at the exit end of the section to cause master .code of the other polarity to be supplied to the next or second section in advance to detect occupancy thereof without causing master code to be repeated into the third section in advance. Master code supplied over the rails of a section causes feed-back energy to be supplied over the section rails, while the polarity of the feedback energy is governed by presence or absenceof feed-back energy in the section in advance and the wayside signals are controlled by the feedback energy. The system is arranged so that when a section is occupied energy is supplied to the section rails at the exit end thereof to detect when'the section is vacated and to discontinue operation of the equipment for that section when the section is vacated.

Where the system is applied to a track stretch through which are operated locomotives equipped with cab signal apparatus responsive to flow of coded alternating current in the track rails, the code frequency of the energy supplied to the rails of an occupied section at the exit end thereof. i

governed by occupancy of the adjacent section in advance.

In the drawings, Figs. 1A and 1B are a diagram of a stretch of track equipped with wayside signaling apparatus embodying this invention,

Figs. 2A and 2B are a diagram of a stretch of track equipped with signaling apparatus embodying this invention and adapted for use in stretches where cab signals are employed, and

Fig. 3 is a diagram of a modification which may be employed in the system shown in Figs.

2A and 2B.

Similar reference characters refer to similar parts in each of the several views.

In most instances the relay contacts are shown directly beneath the winding of the relay, but in somecases, in order to simplify the drawings, relay contacts are shown separated from the relay winding, and where this is done the relay with which the contacts are associated are designated by appropriate reference characters placed directly over the contacts.

In Figs. 1A and 1B of the'drawings there is shown a stretch of railway track having track rails l and 2 over which trafiic normally moves in the direction indicated by the arrows, that is, from left to right. The rails of the track stretch are divided by insulated joints 3 into track sections for signaling purposes. These track sections are designated IT, 2T, 3T, etc. in the drawings, while each of these track sections has at the entrance end thereof a wayside signal designated S with an appropriate prefix. As shown, the wayside signals are of the familiar color light type, and each has a red or stop lamp R, a yellow or caution lamp Y, and a green or clear lamp G.

Each track section is provided with a track circuit having at each end thereof a polar track relay P and a code following neutral or polar biased neutral track relay N connected in series across the section rails. The track relays MP and MN at the exit end of each section are operated by master code supplied over the section rails from the track battery TB, while the track relays F? and FN at the entrance end of each track section are operated by feed-back energy supplied from the feed-back battery PB.

The equipment is shown in the condition which it assumes when the track stretch is vacant. At this time all of the equipment is deenergized so that all of the relays are released and all of the signal lamps are extinguished except the red lamp R of signal IS which controls entrance of traific into the track stretch.

When it is desired to permit a train to enter the track stretch, a slow releasing control relay GR, is picked up and its contact Ill establishes a circuit for a coding device lCT which controls connection of the track battery I'I'B, and of track relays SFP and I FN with the rails of section IT. The pick-up circuit for relay CR may be established by depressing a push-button PB, or it may be established by any other appropriate means as, for example, by a lever of an interlocking machine or by approach of a train.

The coding device ICT and the corresponding devices for the other track sections have contacts biased to a released position in which they connect the track relays across the section rails, while the contacts of each of these coding devices, when the device is energized, are moved to their picked-up positions a predetermined number of times each minute. Although any code speed may be-employed in this system, it is preferred to employ a relatively high code of speed,,such as 180 code impulses per minute, to insure prompt shunting when a train enters a section, and to also insure prompt response of the apparatus on the supply of energy to an unoccupied section.

On picking up of control relay CR and resultant supply of energy to coding device ICT,

its contacts I2 and I3 pick up and cause energy to be supplied from the battery ITB to the rails of section IT. As contacts I5 and I 6 of relay CR are picked up, the energy supplied from battery I TB to the section rails is of normal polarity,

that is, the positive terminal of the battery is :connected to the lower track rail 2. The energy supplied to the section rails feeds over back contacts 1:8 and I9 of impulse relay IIR to track relays IMP and :I MN and moves the contacts of relay IMP to their left-hand or normal position, or holds them in that position if they are already in such position, while this energy picks up the contact of relay IMN so that an impulse of energy is supplied through the decoding transformer .IMDT'to relay IMI-I.

On release of the contacts of coding device 'ICT, the supply of energy from track battery i'TB to the :relays IMP and IMN is cut off and the contacts of relay IMP remain in their normal positions, while the contact of relay IMN releases so that an impulse of energy is supplied through the-decoding transformer IMDT to relay ,IMI-L In addition, on release of relay lMN an impulse of energy is supplied from the decoding transformer IMDI' over back contacts and 2-I of relay 28R. to relay IIR and its contacts I8 and 19 pick up to cause energy to be supplied from battery IFB to the rails of section IT. Energy was also supplied to relay IIR from the transformer :IMDT on picking up of relay IMN, but the relay IIR is of a type which responds to energy of one polarity only, and the equipment is .arrangedso that energy of the polarity effective to pick up the relay contacts is supplied to the relay on release of relay IMN.

On picking up of relay lMI-I, energy is supplied over its front contact 23 and normal polar contact ,25 of relay IMP to relay '2LR, while when relay ZLR. picks up, its contact 26 establishes a stick circuit for the relay including normal polar contact of relay IMP. In addition, on

picking up of relay ZLR, its contact 28 establishes a circuit for coding device 2CT so that it operates to supply master code energy from track battery 2TB to the rails of section- 2T. At this time, relay ZSR is released so the energy .supplied from battery 2TB to the rails of section 2T is of reverse polarity, that is, the positive terminal of the battery is connected to the upper track rail.

The energy of reverse polarity supplied to the rails of section 2T feeds over back contacts 30 and 3i of relay 21R to track relays 2MP and ZMN and moves the contacts of relay 2MP to their right-hand or reverse position and picks up the contact of relay ZMN so that energy is supplied through the decoding transformer ZMDT to relay ZMH, On picking up of relay ZMH, energy is not supplied to relay 3LR. since polar contact 34 of relay 2MP is in its right-hand or reverse position. Accordingly, relay SLR remains released and does not establish the circuit of coding device 3CT so energy is not supplied to the rails of section 3T. As a result, relay SFHP remains released and causes the energy supplied from battery 2FB to the rails of section 2T to be of reverse polarity.

On release of the contacts of coding device ZCT, the track relay ZMN releases and an impulse of energy is supplied from the decoding transformer ZM'D'I' over back contacts 35 and 36 of relay 38R to relay 21R and its contacts 30 and 3| pick up and cause an impulse of energy to be supplied from battery ZFB to the rails of section 2T. This energy feeds over back contacts .38 and 39 of coding device 2CT to track relays ZFP and 2FN and moves the contacts of relay 2FP to their reverse position and picks up t e contact of relay ZF'N so that energy is supplied through the transformer 2FDT to relay ZFH and its contacts pick up and establish a circuit for relay ZFI-IP.

When relay ZFHP picks up, its contacts 40 and 4| cause the energy supplied from battery IFB to the rails of section IT to be of normal polarity, that is, the positive terminal of the battery is connected to the lower track rail 2. Energy supplied from battery IF'B during the picked-up periods of relay lIR feeds over back contacts I2 and I3 of coding device ICT to track relays IFP and IFN and moves the contacts of relay IFP to their left-hand or normal positions and operates relay IFN so that energy is supplied through the transformer IFDT to relay IFH and it is picked up. When relay IFH picks up, its contact 43 completes a stick circuit for relay CR including front contact 44 of relay CR to maintain relay CR picked up after release of the push-button I PB, Accordingly, contact I!) of relay CR maintains the circuit of coding device I CT, while contacts I5 and I5 of relay CR cause the energy supplied from battery I'IB to the rails of section IT to be of normal polarity.

As long as the control relay CR or the relay IFH is reelased, the red lamp R of signal IS is lighted, but when both of these relays pick up, the circuit of the red lamp R of signal IS is interrupted and energy is supplied over front contact 45 of relay CR, front contact 46 of relay IFH, and normal polar contact 48 of relay IFP to the green lamp G of signal IS.

It will be seen, therefore, that when the control relay CR is picked up to initiate operation of the system, master code of normal polarity is supplied to the rails of section IT and causes master code of reverse polarity to be supplied to the rails of section 2T. Master code of reverse polarity supplied to a track section will not cause master code to be supplied to the next section so the supply of master code is not repeated beyond the second track section. Master code of either polarity supplied over the rails of a track section causes feed-back energy to be supplied over the section rails, while the polarity of the feedback energy in a track section is governed by the Red-back detector relay for the section in ad- Vance. Accordingly, feed-back energy of normal polarity is supplied to the rails of section IT and signal IS is caused to display its green or clear indication, while feed-back energy of reverse polarity is supplied over the rails of section 2T with the result that signal 2S, if lighted, will display its yellow or caution indication. At this time, however, relay IMH is picked up and its contact 23 interrupts the circuit of the lamps of signal 28.

If a train now accepts the proceed indication displayed by signal IS and advances into section IT, the supply of both master code and feedback energy over the section rails is out on and relays IMH and IFI-I release.

On release of relay IFH its contact 43 interrupts the stick circuit for relay CR and the contacts of relay CR release to additionally interrupt the relay stick circuit, to deenergize coding device ICT to reverse the connections for supplying energy from the battery ITB to the rails of section IT, and to cause signal IS to display its red or stop indication.

On release of relay IMI-I its contact 23 interrupts the pick-up circuit for relay ZLR but this relay is held picked up at this time by its stick circuit including its own front contact 26, so that energy is supplied over back contact 48 of relay IMH and front contact 49 of relay ZLR to relay 28R.

When relay 23R picks up, its contacts and 52 change the energy supplied from track battery 2TB to the rails of section 2T from reverse to normal polarity with the result that the contacts of relay 2MP move to their left-hand or normal positions so that energy is supplied over front contact 54 of relay 2MH and normal polar contact 34 of relay 2MP to relay 3LR and its contacts pick up. Accordingly, its contact 55 establishes a stick circuit for the relay, while its contact 5! establishes a circuit for coding device 3CT and it operates to supply energy from track battery 3TB to the rails of section 3T. As explained in connection with section 2T, master code of reverse polarity supplied to the rails of track section 3T will not cause master code to be supplied to the next section, but will cause feed-back energy to be supplied over the section rails so that relay 3FH picks up and establishes a circuit for rela fiFI-IP. When relay SFHP picks up, its contacts 59 and 66 change the energy supplied from battery ZFB to the rails of section2T from reverse to normal polarity, and as a result of this change, the contacts of relay ZFP move from their reverse to their normal positions so that the circuit of the green lamp G of signal 2S is established.

As pointed out above, on entrance of the train into section IT, the relay IlVIl-I released, and on release of its contacts energy is supplied over its back contact 23, front contact 62 of relay ZLR, front contact 63 of relay ZFHP, and normal polar contact 65 of relay ZFP to the green or clear lamp G of signal 28 so that the engineer of the train in section IT will be advised that the two adjacent track sections in advance are unoccupied.

As long as section 2T is vacant, the relay ZMH is picked up and prevents the supply of energy to the lamps of signal 3S so this signal is not lighted at this time. As section ET is not occupied, it is unnecessary for the lamps of signal 33 to be lighted.

On entrance of the train into section IT and resultant picking up of relay R, its contacts 20 and 2I transfer control of relay IIR from the decoding transformer IMDT to a circuit con trolled by contacts 6! and 68 of coding device 2CT, and by front contacts I0 and II of relay ZLR. Accordingly, relay HR is operated to supply energy from the battery IFB to the rails of section IT, and to connect track relay IMN and IMP to the section rails, but as the section is occupied, operation of relay IIR has no effect.

From the foregoing, it will be seen that when the train enters section IT, the polarity of the master code supplied to section 2T is changed to thereby cause master code to be supplied to section 3T, while feed-back energy supplied over the rails of section 3T causes the feed-back energy supplied to the rails of section 2T to be of normal polarity so that signal 28 displays its green or clear indication. In addition, when the train enters section IT, the lamps of signal 28 are lighted, while relay IIR is operated by a code transmitter to supply energy to section IT to discontinue operation of the equipment for section IT when that section is vacated, as will be explained hereafter.

When the train advances into section 2T, the supply of energy over the rails of this section is cut off and relays ZFH and ZMI-I release. Release of relay ZFH results in release of relay ZFHP and its contact 63 establishes the circuit of the red lamp R of signal 28, while contacts 40 and M of relay ZFI-IP change the energy supplied from battery IFB to the rails of section IT from normal to reverse polarity.

On release of relay ZMH, energy is supplied over its back contact I3 and front contact I4 of relay 3LR to relay 3SR and its contacts pick up to cause energy of normal polarity to be supplied from battery 3TB to the rails of section 3T, and to transfer control of relay 21R from the decoding transformer ZMDT to the coding device 3CT. On the supply of master code ,of normal polarity to the rails of section 3T, the equipment at the exit end of this section causes master code of reverse polarity to be. supplied to the next section in advance so that feed-back energy is supplied over the rails of that section to thereby cause feed-back energy of normal polarity to be supplied over the rails of section BT and thus cause signal 38 to display its green or clear indication. At this time, energy is supplied to the lamps of signal 38 over the circuit which-includes back contact 54 of relay ZMH and front contact I6 of relay SLR.

When the train vacates section IT, energy of reverse polarity supplied to the section rails from battery IFB as a result of operation of relay I IR by coding device 2CT feeds over back contacts I2 and I3 of coding device ICT to track relays IFN and IFP and operates relay IFN so that relay IFH picks up and its contact I8 establishes a circuit for coding device ICT and it operates to supply energy from batter ITB to the rails of section IT. Atthis time, relay CR is released so its contact 45 maintains the circuit of the red lamp R of signal IS, while its contacts I5 and I6 cause the energy supplied from battery ITB to the rails of section IT to be of reverse polarity.

The energy supplied from battery ITB to the rails of section IT feeds to the track relays IMP and IMN during a released period of the contacts of relay IIR and moves the contacts of relay IMP to their right-hand or reverse position in which contact 25 interrupts the stick circuit for relay 2LR.

On release of relay 2LR, its contacts and II interrupt the circuit controlled by coding device 2CT for operating the relay I IR and the contacts of relay IIR thereafter remain released-and energy is no longer supplied from battery IFB to the rails of section IT and relay IFN ceases to follow code so relay IFH releases and its contact I8 interrupts the circuit of coding device ICT so that it ceases to cause energy to be supplied from battery ITB to the rails of section IT. Accordingly, track relay IMN thereafter remains released and relay IMH releases.

On release of relay ZLR, its contact 49 interrupts the circuits of relay ZSR, but the relay ZSR is of a type the contacts of which are slow to release so contacts and 2| of relay 2S5, remain picked up for a period subsequent to release of relay ZLR and do not connect relay IIR to the secondary winding of transformer IMD'I'. The relay 28B is sufiiciently slow in releasing that its contacts remain picked up and interrupt connection of the relay IIR withtransformer I MDT long enough after release of relay ZLR to insure that relay IFH has released and coding device I CT has ceased to cause energy to be supplied to the rails of section IT. This insures that, when relay IIR is connected to transformer IMDT, there is no possibility that relay IIR will be operated by energy from the transformer and thus cause energy to be supplied to the rails of section IT.

If relay 2SR should release and connect relay I IR to transformer IMDT before track relay IMN ceases to be operated by energy supplied over the section rails, the relay IIR would be operated by impulses of energy from transformer IMDT and would cause energy to be supplied from battery IFB to the rails of section IT. This energy would operate track rela IFN and keep relay IFI-I picked up and thus maintain thecircuit of coding device 'ICT and thereby continue the supply of energy to section IT with the result that the equipment for the section would continue to operate. Any possibility of failure of the equipment to cease operation when a section is vacated may be eliminated by making the release time of relay 28R long enough to be certain that relay IIR is not connected to the decoding transformer until after the track relay IMN ceases to operate.

In addition, on release of relay 211R, its contact 62 interrupts the circuit of the lamps of signal 2S and this signal is now dark, while contact 28 of relay ZLR interrupts the circuit of coding device 2CT and thus discontinues supply of energy to the rails of section 2T.

In like manner, when the train vacates section 2T, energy of reverse polarity supplied from battery ZFB to the section rails as aresult of operation of relay 21R by coding device 3CT feeds to relays ZFP and 2FN and operates relay 2FN to pick up relay ZFH so that its contact 82 establishes a circuit for coding device 2CT. Accordingly, the device ZCT operates to supply energy of reverse polarity from battery 2TB to the rails of section 2T and this energy feeds to track relay 2MP and 2MN during released periods of the contacts of relay 21R. This energy is of reverse polarity because the relay ZSR is released, while this energy causes the contacts of relay 2MP to move to their reverse position in which contact 34 interrupts the circuit of relay 3LR so that relay 3LR releases and discontinues operation of relay 21R by coding device 3CT, while relay 3SR remains picked up, as explained in connection with relay ZSR, to disconnect relay 21R from the decoding transformer 2MDT. The contacts of relay 21R, therefore, remain released and do not cause energy to be supplied from battery 2FB to the section rails but connect the track relays 2MP and ZMN across the section rails.

When the supply of energy to the exit end of section 2T is cut off, the track relay ZFN remains released and relay 2FH releases to interrupt the circuit of coding device ZC'I' and thus cut off the supply of energy from battery 2TB to the rails of section 2T. This causes relay 2MN to cease to follow code so relay 2MH releases, while relay 38R thereafter releases to reconnect relay 2IR. to transformer ZMDT, and to cause the energy supplied from battery 3TB to the rails of section BT to be of reverse polarity.

The equipment for each of the other sections in the track stretch operates in a similar manner so that, When'a train enters a track section, energy is supplied over the section rails to detect when the section is vacated and to thereupon discontinue operation of the track circuit apparatus for that section.

This system also operates to provide appropriate signal indications for a second or following train. For purposes of illustration, it will be assumed that the train considered above stops in section 31 and that a second train is admitted to the track stretch. In order to cause signal IS to display a permissive indication, the push-button PB is depressed to pick up control relay CR and cause master code of normal polarity to be supplied to the rails of section IT. This causes master code of reverse polarity to be supplied to the rails of section 2T so that feed-back energy is supplied over the rails of section 2T and causes feed-back energy of normal polarity to be supplied over the rails of section IT and thus cause signal IS to provide its green or clear indication.

If the second train new enters section IT, the supply of master code of normal polarity over the rails of this section is cut off and relay IMH releases and establishes the circuit including front contact 49 of relay ZLR for energizing relay 28R.

- When relay 28R picks up, it changes the energy supplied from battery 2TB to the rails of section 2T from reverse to normal polarity. Master code of normal polarity supplied to the rails of section 2T causes the contacts of relay 2MP to occupy their left-hand or normal positions so that energy is supplied to relay 3LR overthe circuit which includes front contact 54 of relay 2MH and normal polar contact 34 of relay 3LR. Accordingly, the contacts of relay SLR pick up and energy is supplied over its front contact 51 to coding device 3CT and it operates to supply energy of reverse polarity from battery 3TB to the rails of section 3T.

However, as section 3T is assumed to be occupied, master code supplied to the section rails does not reach the exit end of the section and does not cause feed-back energy to be supplied over the section rails. Accordingly, relays 3FH and 3FHP remain released and the feed-back energy supplied from battery ZFB to the rails of section 2T is of reverse polarity so the contacts of relay 2F? remain in their right-hand or reverse positions and contact establishes the circuit of the yellow lamp Y of signal 28. When the first train is in section 3T, the second or following train will receive a caution indication from signal 28 and will be prepared to stop before entering section 3T.

As pointed out above, when the first train enters section 3T, the equipment at the exit end of that section is conditioned to cause the relay 31R, not shown, to be operated by the coding device for the adjacent section in advance to supply energy of reverse polarity to the rails of section 3T.

If, while the second train is in section IT, the first train vacates section 3T, the signal equipment will operate to provide the proper signal indications for the second train. When the first train vacates section 3T, master code of reverse polarity supplied at the entrance end of the section as a result of energization of coding device 3CT over the circuit established by contact 51 of relay 3LR, feeds Over the section rails, while energy from battery 3FB, not shown, supplied to the section rails at the exit end of the section as a result of operation of relay 31R by the coding device for section 4T also feeds over the section rails.

The energy of reverse polarity supplied to the section rails at the entrance end of the section feeds to the track relays at the exit end of the section and moves the contacts of relay 3MP, not shown, to their reverse position to interrupt the circuit of relay fiLR, not shown, and thereby discontinue operation of relay 3TB by the coding device and to also interrupt the circuit of relay 4SR. After a short time interval, relay ffiSR releases and connects relay 31R to the associated decoding transformer so that the relay 31R thereafter functions as a feed-back impulse relay and continues to cause impulses of energy of reverse polarity to be supplied to the rails of section 3T at the exit end thereof.

The energy of reverse polarity suppliedto the rails of section 3T at the exit end thereof feeds to track relays 3FP and 3FN and operates relay 3FN so that relay SFI-I picks up and causes the slow release repeater relay SFHP to pick up. When relay BFHP picks up, its contacts 59 and 80 change the energy supplied from battery 2FB to the rails of section 2T from reverse to normal polarity so that the contacts of relay ZFP move to their left-hand or normal positions and establish the circuit of the green or clear lamp G of signal 28.

As explained above, when a train vacates a section and energy of reverse polarity is supplied from the entrance end of the section to the exit end thereof, the relay LR releases to discontinue operation of relay IR by the coding device, while a time interval must elapse before relay SR releases to connect relay IR to the decoding transformer. In this time interval relay IR does not operate to supply energy to the section rails and the relay FH at the entrance end of the section releases. However, the relays FH control slow releasing repeater relays FI-LP, which are slow enough in releasing to remain picked up during this release of the relays FI-I. Accordingly, the relays FI-IP prevent momentary flashes of the red signal lamps, and momentary reversal of the polarity of the feed-back energy supplied to the section in the rear and consequent momentary display of the yellow indication by the signal for that section.

From the foregoing, it will be seen that if a second train is in section IT and the first train vacates section 3T, the equipment operates to change the indication provided by signal 2S from yellow to green so that the engineer of the-second train is informed of the change in traffic conditions in advance.

This system also operates to provide proper control of the signals if the second train advances into section 2T before the first train vacates section 3T.

As pointed out above, when the second train entered section IT, the supply of master code of normal polarity over the rails of section IT is cut' to supply master code of reverse polarity to the rails of section ?.T, but as section ST is assumed to be occupied, this supply of master code to the section rails is without effect.

If, while the first train is in section 3T, the second train advances into section 2T, the supply of master code over the rails of section 2T will be cut off and relay ZMH will release so that energy is supplied over its back contact 13 and front contact '14 of relay 3LR to relay 38R and it picks up to cause the energy supplied to section 3T to be of normal polarity. As long as section 3T is occupied, master code of normal polarity supplied to the section rails has no effect, but when the first train vacates section 3T, this energy feeds to the exit end of the section and causes the contacts of track relay 3MP, not shown, to move to their normal positions to establish the pick-up circuit of relay 411R, not shown, while relay 3MH picks up to interrupt the circuit of relay @SR. At the expiration of the release time of relay GSR, the relay 3IR operates as a feed-back impulse relay and causes feed-back energy of appropriate polarity to be supplied to the rails of section 3T to control signal 38, and the equipment thereafter operates in the usual manner.

This system also operates to provide the proper control of the signals if a train enters a track section before the preceding train vacates the track section. For purposes of illustration, it will be assumed that a train stops in section 2T, and that a second train enters this section before the first train vacates the section.

As previously explained, when the first train entered section 2T, the relay SSR picked up so that relay ZIR is operated by coding device SOT and causes energy to be supplied from battery ZFB to the rails of section 2T. As section 2T is assumed to be occupied by the first train, the energy supplied to the section rails from battery ZFB is without effect, whiie entrance of the second train into section 2T has no effect. If the second train should vacate section ET, operation of the equipment for that section would be discontinued in the usual manner.

When the first train vacates section 2T, the relay 21R. continues to be operated by coding device tCT and energy continues to be supplied from battery 2F'B to the rails of section 2T, but because of the presence of the second train in the section, this energy is without effect and there is no change in the condition of the equipment for 7 section 2T.

master code supplied to the entrance end of the section will cause the equipment at the exit end of the section to supply master code to the next section in advance and to supply feed-back energy over the rails of section 3T to cause signal 38 to display a permissive indication.

As pointed out above, when the first train vacates section 2T, the relay 3LR is picked up, while relay ZMH is released so the circuit for supplying energy to the lamps of signal 35 is complete and a lamp of this signal is lighted to indicate to the engineer of the second train the condition of occupancy of the adjacent section in advance.

When the second train vacates section 2T, the equipment for this section operates in the usual manner to detect when the section is vacated and to thereafter discontinue operation of the equipment for that section.

The principle employed in the system shown in Fig. 1 may be employed in a signaling system operating without wayside signals and adapted for use in track stretches through which are operated locomotives equipped with cab signal apparatus responsive to flow of coded alternating current in the track rails and Fig. 2 is a diagram showing this modification of the invention.

System shoum m Fig. 2

In the modification shown in Fig. 2, the stretch is without wayside signals except for a signal IS which governs entrance of trains into the protected stretch.

The construction and operation of the cab signal apparatus on the locomotives operated in the track stretch are not a part of this invention and this apparatus may be constructed as shown in Letters Patent of the United States No. 1,986,679 of L. V. Lewis.

The equipment is shown in the condition which it assumes when the track stretch is vacant and before it is prepared for passage of a train therethrough. At this time all of the relays are released and all of the coding devices are deenergized, While the red lamp R of signal IS is lighted by energy supplied over back contact 45 of relay CR.

When it is desired to prepare the stretch to permit passage of a train therethrough, the pushbutton PB is depressed to establish a pick-up circuit for the slow releasing control relay CR and its contacts pick up so that energy is supplied over its front contact to coding device ICT with the result that it operates to supply energy from the battery I'I'B to the rails of section lT through the winding of relay IFT in the wrong direction to pick up the contacts of the relay IFI. The energy supplied to the rails of section IT feeds over back contacts I00 and IUI of coding relay (CT? to relay l MT and operates it so that energy is supplied through the decoding transformer IMDT to relay IMHand to relay HR. The relay IIR is of a type the contact of which will be picked up only on supply of energy of one polarity thereto, and the equipment is arranged so that energy of this olarity is supplied to the relay on release of the contact of relay IMH. Accordingly, on continued operation of relay IMT subsequent to picking up of the contacts of relay IMH, an impulse of energy is supplied to coding relay I CTP each time the contacts of relay I MT release. The circuit for supplying energy to relay I CTP includes front contact I63 of relay IMH, front contact I04 of relay IIR, back contact I05 of relay 28R, and back contact I 05 of relay 2Q.

The energy supplied to relay ICTP picks up its contacts momentarily and, during the pickedup periods of the relay contacts, energy is supplied from battery IFB- to the rails of section IT. This energy feeds to relay IFT over the back contact of coding device ICT and operates relay Il' I' so that energy is supplied through the decoding transformer I'FDT to relay IFH. The contacts of relay IFH, therefore, pick up so that front contact 43 of relay IFH completes the stick circuit including front contact 44 of relay CR to maintain the relay CR picked up. In addition, on picking up of relay IFH, the circuit of the red lamp R of signal IS is interrupted and energy is supplied over front contact 45 of relay CR and front contact 46 of relay IFH to the yellow lamp Y of signal IS to thereby indicate that the stretch is prepared for passage of a traintherethrough.

0n the supply of energy to section IT and operation of relay IMT to pick up relay I MI-I, energy is sup-plied over front contact I08 of relay IMH and back contact I69 of relay 2Q to relay ZLR, while on picking up of relay ZLR, its contact Illl establishes a stick circuit to maintain the relay picked up as long as relay 2Q is released.

At this time, relay ZSR is released so the tuned alternator controlled thereby is deenergized, while the primary winding of track transformer I TI is short-circuited over back contact II I of relay 2SR to reduce impedance of the transformer secondary winding and minimize arcing at the contacts of relay ICTP.

If a train now enters section IT, the supply of energy over the rails of this section will be cut off and relay IFH will release so that its contact 43 interrupts the stick circuit for relay CR so it releases and cuts oil operation of coding device ICT, While the circuit of the yellow lamp Y of signal IS is interrupted and the circuit of the red lamp R is established.

In addition, at this time relay IMH releases with the result that energy is supplied over its back contact I08 and front contact H2 of relay ZLR to relay 28R and its contacts pick up so that its front contact H4 establishes a stick circuit to maintain the relay picked up as long as relay ZLR is picked up. On picking up of relay 28R, its contact H5 establishes the circuit of code transmitter ICT, while its contact Ill establishes the circuit of code transmitter ISCT.

On operation of code transmitter I BUCT, the coding relay ZFCT is operated to supply energy to the rails of section 2T and this energy feeds over back contacts I20 and I2I of relay 2CTP to relay ZMT so that energy is supplied through transformer ZMDT to relays 2MH and 21R. Accordingly, relay ZMH picks up while relay 21R operates to supply impulses of energy to relay ZCTP over the circuit which includes front contact I23 of relay ZMH, front contact I24 of relay 21R, back contact I26 of relay 35R, and back contact I21 of relay 3Q. V

'I'he'energy supplied to relay 2CTP causes it to supply energy from battery ZFB to the rails of section 2T and this energy feeds over the back contact of relay ZFCT to relay 2F'T and operates it so that energy is supplied through transformer ZFDT to pick up relay ZFH.

In addition, on picking up of relay 2MH energy is supplied over its front contact I28 and back contact I29 of relay 3Q to relay 3LR and it's contacts pick upso' that its front contact I30 establishes a stick circuit to keep the relay energized as long as relay 3Q is released.

When relay ZSR picked up, its contact I06 transferred control of coding relay ICTP from relay IIR to one of the code transmitters. As section 2T is vacant and relay 2FH is picked up, energy of 180 code frequency is supplied to relay ICTP over the circuit which includes front contact I32 of relay 2FH, front contact I06 of relay 23R, and back contact I of relay 2Q.

In addition, When relay ZSR picked up, its contact I I I connected the primary winding of transformer ITT across the output terminals of the tuned alternator, while contact I33 of relay 2SR established the circuit to supply energy to the alternator so that energy is supplied from the alternator to the track transformer. As coding relay ICTP is operated at the 180 code rate, a1- ternating current of 180 code frequency is supplied from track transformer ITT to the rails of section IT and operates the locomotive cab signal apparatus to provide its clear indication.

When the train advances into section 2T, the supply of energy over the rails of this section is cut off and relay 2FI-I releases so that its contact I32 transfers control of relay ICTP to the code transmitter IECT, while contact I34 of relay ZFH establishes a circuit including front contact I II of relay ZSR for supplying energy to this coding device. tact I35 interrupts one circuit for supplying energy to code transmitter I89CT, but this device is energized by energy supplied thereto over front contact I I5 of relay ZSR. Accordingly, relay 2FCT continues to operate to supply energy from battery 2TB to the rails of section 2T.

When the train enters section 2T, relay ZMH releases and energy is supplied over its back contact I28 and front contact I37 of relay SLR to relay 33R so that relay 38R picks up and its contact I38 establishes a stick circuit to keep the relay energized as long as relay 3LR is picked up.

On picking up of relay 33R, its contact I40 establishes a circuit for the associated coding device I8IICT and it operates to cause relay 3FCT On release of relay ZFH, its con-' to supply master code to the rails of section 3T and thus determine occupancy of this section. If the section is vacant, the equipment for section 3T will operate as explained in connection with section 2T to cause feed-back energy to be supplied over the section rails with the result that relay 3FH is picked up.

When relay 38R picked up, its contact I26 transferred control of relay ZCTP from relay 21R to one of the code transmitters, While when relay 3FH picks up, energy of 180 code frequency is supplied to relay ZCTP over the circuit in cluding front contact I lI of relay 3FI-I, front contact I26 of relay 33R, and back contact I21 of relay 3Q. As relay 38R is picked up, the tuned alternator at this location operates to supply energy to the primary winding of track transformer 2TT, and as relay ZCTP is operated at the 180 code rate, alternating current of 180 code frequency is supplied to the rails of section 2T to cause the cab signal apparatus on the locomotive in that section to provide its clear indication.

When the train advances into section 3T, the equipment for that section operates in the same manner as the equipment for section 2T to cause alternating current of appropriate code frequency to be supplied to the section rails at the exit end thereof. When section 3T is occupied, relay SFI-I is released and its contact I4I establishes the circuit for supplying energy of 75 code frequency to relay ZCTP.

When the train vacates section IT, the energy of '75 code frequency supplied from battery IFB to the section rails operates relay IFT so that relay IFH picks up and its contact I8 establishes a circuit for coding device ICT. Ac-

cordingly, the device ICT operates to supply energy from battery ITB to the section rails, and during released periods of the relay ICTP, this energy feeds to track relay IMT and operates it so that relay IMl-I picks up. When relay IMH picks up at a time when relay 23B. is pickedup, energy is supplied over front contact N4 of relay ZSR and front contact I IZ of relay IMH to relay 2Q, and its contacts pick up so that its contact I44 establishes a stick circuit including front contact IE3 of relay ZSR to maintain the relay 2Q picked up as long as relay ZSR is picked up.

In addition, when relay 2Q picks up, its contact H19 interrupts the circuit of relay 2LR while contact I05 of relay 2Q interrupts the circuit of relay ICTP so that it ceases to cause energy to be supplied from battery IFB to the rails of section IT. Accordingly, relay IFT remains released and relay IFH releases and its-contact l8 interrupts the circuit of coding device ICT so that energy is no longer supplied to the section rails at the entrance end of the section and relay IMT remains released and relay IMH releases.

On release of relay IMHM, its contact I42 interrupts the pick-up circuit of relay 2Q, but this relay is energized by current supplied over its stick circuit so its contacts remain picked up to interrupt the circuits of relays ZLR and ICTP.

As stated above, on picking up of relay IMH when relay 28R is picked up, energy is supplied to relay 2Q and it picks up to interrupt the circult of relay ZLR. The relay ZLR is of a type the contacts of which are slow to release so they remain picked up for a short period subsequent to picking up of relay 2Q. On release of relay ZLR, its contact H2 interrupts the circuit of relay 2SR and after a time interval the contacts of relay ZSR release so that contact I43 interrupts the stick circuit for relay 2Q and relay 2Q thereupon releases and the equipment at the exit end of section IT is again in its normally deenergized condition.

On release of relay ZSR, its contacts H5 and III interrupt the circuits of code transmitters 'IECT and I80CT, while contact I33 interrupts the circuit of the tuned alternator and contact III short-circuits the primary winding of the 7 track transformer ITT. In addition, on release of relay 25R, its contact I06 transfers control of relay ICTP from the code transmitters to the impulse relay IIR, but the circuit of relay ICTP is not complete until relay 2Q releases.

As pointed out above, relay 2Q picked up when energy supplied over the rails of section IT operated relay IMT to pick up relay IMH, While as soon as relay 2Q picks up its contact I05 interrupts the circuit of relay ICTP so that energy is no longer supplied to the rails of section IT and, after a short time, relay IFH releases to discontinue operation of coding device ICT and thus cut off supply of energy to the entrance end of section IT so that relay IMH releases to cause its contact I63 to interrupt the circuit controlled by impulse relay IIR for supplying energy to the relay ICTP.

After relay 2Q picks up to interrupt the circuit of relay I CTP, the circuit of relay ICTP is not reestablished until relay 2Q releases, while relay 2Q remains picked up until relays 2LR and 28R release. The circuit of relay ZSR is maintained until relay ZLR releases, while the circuit of relay 2Q is maintained until relay 28R releases so these relays release successively. The relays ZLR, ZSR and 2Q are of a type the contacts of which are slow in releasing, and the various parts of the system are proportioned so that relay 2Q does not release to establish the circuits of relays I CTP and ZLR until relay I MH releases to interrupt the cricuits of these relays. This insures that the equipment for section IT will be returned to its normally deenergized condition when the section is vacated.

When the train vacates section 2T, the equipment for this section operates in the same manner as the equipment for section 1T so that the track section apparatus is deenergized.

The system shown in Fig. 2 operates so that when a train enters the section in the rear of an occupied section, alternating current of '75 code frequency will be supplied to the section rails to cause the locomotive cab signal apparatus to provide its caution indication.

For purposes of illustration, it will be assumed that a train is in section 2T and that a second or following train enters section IT. As explained above, when the first train vacated section IT, the equipment for section IT was restored to its normally deenergized condition, while relays 2Q, ZLR; and ZSR became released. When it is desired to permit the second train to enter section IT, the push button PB is depressed to pick up the control relay CR so that coding device ICT operates to supply energy to the rails of. section IT. This energy operates relay IMT to pick up relay IMH and thus pick up relay 211R, while after relay I MH picks up, relay ICTP is operated to supply impulses of feed-back energy to the section rails to operate relay IFT and pick up relay IFH and thus cause signal IS to display a permissive indication.

When the second train enters section IT, the relay IMH releases and relay ESR. is picked up so that coding device I85CT operates to cause relay 2FCT to supply energy to the rails of section 2T; However, as section 2T is assumed to he occupied, the energy supplied at the entrance end of the section does not reach the equipment at the exit end of the section so feed-back energy is not supplied over the section rails. Accordingly, relay 2FH remains released and its contact I32 connects relay ICTP to-the contact of code transmitter 150T and energy of 75 code frequency is supplied to the rails of section IT, and the cab signal apparatus on the locomotive in section IT will provide its caution indication.

If the first train should vacate section 2T while the second train is in section IT, energy supplied to the rails of section 2T as a result of operation of relay 2FCT feeds to relay 2MT and operates it to pick up relay ZMH and establish a circuit for relay 3Q so that it picks up to prevent operation of relay 2CTP and to. cause release of relays 3LR and SSH.

At this time, code transmitter ISGCT at the entrance end of section 2T is operated by energy supplied thereto over the circuit controlled by relay 28R. so that this device continues to operate after relay 2CTP ceases to operate. Accordingly, relay 2MH remains picked up after release of relays 3LR, 38R and 3Q and, as soon asrelay 3Q releases, energy is supplied to relay ZCTP over the circuit controlled by relay 21R. so that relay ZCTP operates to supply feed-back energy to the rails of section 2T. This energy operates relay ZFT so that relay ZFH picks up to transfer control of relay ICTP from the coder 'I-ECT to the coder I80CT with the result that energy of 180 code frequency is supplied to the rails of section 1 T and the indication displayed by the cab signal apparatus on the locomotive inthat section is changed from caution to clear.

The system shown in Fig. 2 also operates so that, if a train enters an occupied section, the equipment will function to cause the cab signal apparatus on the locomotive of the second train to provide an appropriate indication.

For purposes of illustration, it will be assumed that a train is in section 2T and that a second or following train enters the section. The rails of section 2T are shunted by the first train in the section so the cab signal apparatus on the locomotive of the second train will provide its most restrictive indication when the locomotive enters section 2T.

As explained above, when the first train entered section 2T, the relay 38R picked up so that relay ZCTP is operated by energy supplied over a circuit controlled by one of the code transmitters and energy from both the battery ZFB and the transformer ZTT is supplied to the rails of sec- "tion 2T. As long as section 3T is vacant, relay 3FH is picked up so relay ZCTP is operated at the 180 code rate, but when the first train in section 2T advances into section 3T, the relay 3FH releases and transfers control of relay ZC'I'P to code transmitter l5CT so that energy of 75 code frequency is supplied to the rails of section 2T. When the first train vacates section 2T, the energy supplied to the section rails as a result of operation of relay ZCTP causes the cab signal apparatus on the locomotive of the second train to: provide its caution indication.

Because of the presence of the second train in section 2T, the energy supplied from battery ZFIB to the section rails does not reachrelay 2FT and relay ZFCT is not operated to supply energy from battery 2TB over the rails of section 2T to operate relay 2MT and pick up relay 2MB. Relay ZMH therefore remains released and does not establish the circuit of relay 3Q and the equipment at the exit end of section 2T continues to operate to supply to the rails of section 2T energy of a code frequency determined by trafiic in section 3T. When section 2T is vacated, the equipment for the section operates in the usual manner to cease operation and assume its normally denergized condition.

Modification shown in Fig. 3

In Fig. 3, there is shown a modified form of apparatus which I may enjoy. This modification is similar to that shown in Fig. 2 but differs therefrom in the control of the relay FCT. Under vacant track conditions, the relay LR is released and connects relay FCT to a secondary winding of the recoding transformer FDT. 0n approach of a train, the relay LR. is picked up, as explained in connection with Figs. 1 and 2, and connects relay FCT to the circuit controlled by the code transmitter IilIlCT so that relay FCT operates to supply coded energy to the rails of the associated track section. 'On movement of a train through the track stretch, the relay LR releases when the section in the rear is vacated, while on release of relay LR, control of relay FCT is transferred to the decoding transformer PDT. As long as the section is occupied, relay FT remains released and no energy is supplied from the decoding transformer FD'I' to relay FC'I. When the section with which relay FCT is associated is vacated, energy supplied at the exit end of the section feeds over the section rails and operates relay FT so that an impulse of energy effective to pick up the contacts of relay FCT is supplied to the relay each time the contacts of relay FT release. As a result of operation of relay FCT, energy is supplied from battery TB to the section rails, while, as explained in connection with Fig. 2, this energy causes the equipment at the exit end of the section to operate to discontinue the supply of energy'to the section rails at that point so that relay FT ceases to operate and energy is no longer supplied from the transformer FDT to the section rails.

It will be seen that this modification is arranged so that, when a section is vacated, the relay FCT ceases to operate and therefore discontinues the supply of energy to the section rails substantially as soon as the supply of energy to the exit end of the section is cut off. It is unnecessary to wait for release of relay FI-I before operation of relay FCT to supply energy to the section rails is discontinued. The prompt termination of the supply of energy to the section rails as a result of operation of relay FCT is desirable as it makes deenergization of the apparatus for a track section prompt and positive.

Although I have herein shown and described only two forms of normally deenergized coded signaling system embodying my invention together with a modification thereof which I may employ, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

'I-Iaving thus described my invention, what I claim is:

1. In combination, a stretch of railway track through which trafiic normally moves in a given direction, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections each of which is provided with normally inactive coded track circuit apparatus, means for each section operative on approach of a train to cause coded energy to be supplied to the section rails at the entrance end of the section, the track circuit apparatus for each section being arranged so that on supply of energy to the section rails at the entrance end of the section the equipment at the exit end of the section causes coded energy to be supplied to the section rails at the exit end of the section, trafiic governing means for each section responsive to the supply of energy over the rails of the adjacent section in advance from the exit to the entrance end thereof, and means for each section efiective on occupancy of the section to supply coded energy to the section rails at the exit end of the section, the track circuit apparatus for each section being arranged so that such supply of coded energy to the section rails at the exit end thereof causes coded energy to be supplied to the section rails at the entrance end of the section when the section is vacated and so that such energy causes the equipment at the exit end of the section to operate to discontinue supply of energy to the section'rails at the exit end of the section.

1 2. In combination, a stretch of railway track divided into a forward and a rearward section each of which is provided with normally inactive coded track circuit apparatus, means governed by occupancy of the rearward track section for supplying coded energy to the rails of the forward section at the entrance end thereof, means at the exit end of the forward section responsive to supply of coded energy over the section rails to supply coded energy to the section rails at the exit end thereof, traffic governing means for said rearwardsection responsive to supply of energy over the rails of the forward section from the exit to the entrance end of said forward section, means effective on occupancy of the forward section to supply coded energy. to the section rails at the exit end of the section, means at the entrance end of the forward section responsive to supply of energy over the section rails from the exit end thereof to supply coded energy to the section rails at the entrance end thereof, and means at the exit end of the section responsive to the supply of energy over the section rails subsequent to occupancy of the section for cutting, off the supply of energy to the section rails at the exit end of the section.

3. In combination, a stretch of railway track divided into a forward and a rearward track section each of which is provided with normally inactive coded track circuit apparatus, a control relay at the exit end of said rearward section which becomes picked up on the supply of coded energy over the rails of said rearward section from the entrance to the exit end thereof, a first and a second normally released auxiliary relay associated with said control relay, means governed by trafiic in the track stretch for supplying coded energy to the rails of said rearward section at the entrance end of the section to pick up said control relay and establish a pick-up circuit for said first auxiliary relay, a stick circuit for said first auxiliary relay including its own front contact, means effective when said first auxiliary relay is picked up to supply coded energy to the rails of said forward section at the entrance end thereof, means responsive to supply of coded energy over the rails ofthe forward section from the entrance to the exit end thereof for supplying coded energy to the rails of the forward section at the exit end thereof, traffic governing means controlled by energy supplied over the rails of said forward section from the exit to the entrance end thereof, a circuit for said second auxiliary relay governed by a back contact of said control relay and a front contact of said first auxiliary relay, means effective when said second auxiliary relay is picked up to supply coded energy to the rails of said rearward section at the exit end thereof, means at the entrance end of said rearward section effective during supply of coded energy over the section rails to supply coded energy to the rails of said rearward section at the entrance end thereof, and means at the exit end of the rearward section operated byenergy supplied over the section rails from the entranceto the exit end thereof as a result of supply of energy over the section rails from the exit to the entrance end thereof for interrupting the stick circuit for said first auxiliary relay.

4. In combination, a stretch of railway track divided into a forward, an intermediate and a rearward track section, control means at the exit end of the intermediate section selectively responsive to coded energyof a first or a second type supplied over the section rails from the entrance to the exit end thereof, means responsive to traflic conditions in said rearward section for at times supplying coded energy of said first type and at other times supplying coded energy of said second type to the rails of said intermediate section at the entrance end thereof, a first and a second normally released auxiliary relay associated with said control means, a pick-up circuit for said first auxiliary relay established only on response of said control means to coded energy of said first type, said first auxiliary relay when picked up establishing for itself a stick circuit which is interrupted on response of said control means to coded energy of said second type, means effective when said first auxiliary relay is picked up to supply to the rails of the forward section at the entrance end thereof coded energy of said first or said second type according as said second auxiliary relay is picked up or released, means responsive to supply of coded energy over the rails of the intermediate section while the second auxiliary relay is released to supply coded energy to the rails of the intermediate section at the exit end thereof, trafiic governing means responsive to supply of coded energy over the rails of said intermediate section from the exit to the entrance end thereof, means efiective'fon deenergization of said control means when the first auxiliary relay is picked up to establish a circuit for said second auxiliary relay, means for supplying coded energy to the rails of said intermediate section at the exit end thereof when said second auxiliary relay is picked up provided the first auxiliary relay is also picked up, and means at the entrance end of said intermediate section responsive to supply of. coded energy over the section rails to supply coded energy of said second type to the section. rails.

5. In a normally deenergized coded railway signaling system, in combination, a stretch of railwaytrack divided into a plurality of track sections through which traff c normally moves in a given direction, means for projecting coded detector energy over the rails ofthe track stretch away from the entrance end of the stretch for a selectednumber of track sections, means fOr each section responsive to the supply of coded detector energy over the section rails for supplying coded control energy over, the section, rails towards the entrance endof the stretch, traffic governing means responsive to supply of coded control energy over the rails of saidtrack,sectionsmeans operative on entrance of a train. into each section to, cause'the supply. of coded detectorenergy to be, projected into another track section, and means for eachsection for detecting when the section has been vacated and for thereupon discontinuing operation of the track circuit apparatus for the said section. r

, 6. In a normally deenergized codedc-railwa signaling system, in combination, a stretch of railway track dividedinto a plurality of track sections thro gh which trafiic normally moves in a given direc ion, means for projecting coded detector energy away. from the, entrance end of the stretch over the rails of, the two track sections nearest the entrance end. of the stretch, means for each section responsive to the supply of coded detector energy over, the section rails for supplying over the section rails towards the entrance end of the stretch coded control energy, the supply of coded control energy to the rails of each of said track sections being governed by means responsive to the supply of coded control energy over the rails of the adjacent track section in advance thereof, traffic governing means for each section responsive to the-supply of coded control,

energy over the rails of said section, means operative on entrance of a train intoeachtrack sec tion to cause coded detector energy to be'- supplied to the second'track'section inadvance thereof, and means for-each track section fordete'cting when the section has been vacated and for thereupon discontinuing operation ot the track circuit apparatus for the said section;

7. In a normally deenergized' coded railway signaling system, in combination, a stretch of railway track divided into a plurality of track sec-- tions through which traffic normally moves in a given direction, means for projecting coded detector energy away from the entrance end of the stretch over the rails of the two track sections nearest the entrance end of the stretch, meansfor each section responsive to thesupplyof codeddetector energy over the section rails for supplying over the section rails towards the entrance end of the stretch coded control energy of'a first or asecond type according as coded control energy is or is not being transmitted over the rails of the adjacent track section in advance, trafiic governing means for each section governed by the supply of coded control energy over the rails of the said section and selectively responsive to the type of such energy, means operative on entrance of a train into each track section to cause coded detector energy to be supplied to the second track section in advance, and means for each track section for detecting when the section has been vacated and for thereupon discontinuing operation of the. track circuit apparatus for the said section.

8. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track divided into, a plurality of track sections through which trafiic normally moves in a given direction, means for projecting coded detector energy of normal polarity away from the entrance end of the track stretch over the rails of the track section nearest the entrance end of the stretch, means for each section operative on the supply of codeddetector energy of normal polarity over the section rails to cause coded detector energy of reverse polarity. to be projected away from the entrance end of the track stretch over the rails of the adjacent section in ad'- vance, means for each section responsive to the supply of coded detector energy of either pclarity over the section rails for supplying over the section rails towards the entrance end of the stretch coded'control energy, means for each section responsive to the supply of coded control energy over the rails ,of-the saidisection and controlling the polarity of the coded control ener y supplied tothe rails of the adjacent track section in the rear, t'ralfic governing means for each section governed by, the supply of; coded control energy over the rails of. the said sectionand selectively responsive to. the polarity of. such energy, means for each section operative on entrance of a train into the said section to cause the coded detector energy supplied to. theQadj'acentsection inadvance to be changed, fromre- Verse tonormal, polarity, and means. for each track section for detecting when the section has been vacated and for. thereupon discontinuing operation of the track circuit apparatusfor the saidsection.

9 In, a normally deenergized, coded railway signaling system, in combination, a stretch; of. railway track divided into aplurality of track sections through which traflic normally movesin a given direction, meansfor projecting. coded the entrance end of the track stretch over the rails of the track section nearest the entrance end of the stretch, each section having at the exit end thereof a first auxiliary relay having a pick-up circuit which is established when and only when coded detector energy of normal polarity is supplied over the rails of the said section, each first auxiliary relay when picked up establishing for itself a stick circuit which is interrupted on supply of coded energy of reverse polarity over the rails'of the associated track section, each track section having at the exit end thereof a second auxiliary relay which is energized when the supply of coded detector energy over the rails of said section is cut ofi provided the associated first auxiliary relay is picked up, each first auxiliary relay when energized causing to be supplied to the rails of the adjacent track section in advance coded detector energy of normal or reverse polarity according as the associated second auxiliary relay is picked up or released, means for each section responsive to the supply of coded detector energy of either polarity over the section rails and to the supply of coded control energy over the rails of the adjacent section in advance for supplying coded control energy over the rails of the associated section towards the entrance end thereof, means responsive to coded control energy supplied over the rails of said track sections for governing traffic in said track stretch, and means for each track section for detectin when the section has been vacated and for thereupon discontinuing operation of the track circuit apparatus for the said section.

10. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track divided into a plurality of track sections through which trafiic normally moves in a given direction, means for projecting coded detector energy of normal polarity away from the entrance end of the track stretch over the rails of the track section nearest the entrance end of the stretch, each section having at the exit end thereof a first auxiliary relay having a pick-up circuit which is established when and only when coded detector energy of normal polarity is supplied over the rails of the said section, each first auxiliary relay when picked up establishing for itself a stick circuit which is interrupted on supply of coded energy of reverse polarity over the rails of the associated track section, each track section having at the exit end thereof a second auxiliary relay which is energized when the supply of coded detector energy over the rails of said section is cut off provided the associated first auxiliary relay is picked up, each first auxiliary relay when energized causing to be supplied to the rails of the adjacent track section in advance coded detector energy of normal or reverse polarity according as the associated second auxiliary relay is picked up or released, means for each'section responsive to the supply of coded detector energy of either polarity over the section rails for supplying over the section rails-towards the entrance end thereof coded control energy of normal or reverse polarity according as coded control energy is or is not being supplied over the rails of the adjacent track section in advance, means responsive to coded control energy supplied over the rails of said track sections and selectively responsive to the polarity of such energy for governing traffic in said track stretch, and means for each track section for detecting when the section has been vacatedand for thereupon discontinuing operation of the track circuit apparatus for the said section.

11. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track divided into a plurality of track sections through which traffic normally moves in a given direction, means for projecting coded detector energy of normal polarity away from the entrance end of the track stretch over the rails of the track section nearest the entrance end of the stretch, each section having at the exit end thereof a first auxiliary relay having a pick-up circuit which isestablished when and only when coded detector energy of normal polarity is supplied over the rails of the said section, each first auxiliary relay when picked up establishing for itself a stick circuit which is interrupted on supply of coded energy of reverse polarity over the rails of the associated track section, each track section having at the exit end thereof a second auxiliary relay which is energized when the supply of coded detector energy over the rails of said section is cut ofi provided the associated first auxiliary relay is picked up, each first auxiliary relay when energized causing to be supplied to the rails of the adjacent track section in advance coded detector energy of normal or reverse polarity according as the associated second auxiliary relay is picked up or released, means for each section responsive to the supply of coded detector energy of either polarity over the section rails and to the supply of coded control energy over the rails of the adjacent section in advance for supplying coded control energy over th rails of the associated section towards the entrance end thereof, means responsive to coded control energy supplied over the rails of said track sections for governing traffic in said track stretch, means for each section operative when the first and second auxiliary relays for such section are picked up to supply coded resetting energy to the section rails at the exit end thereof, and means for each section responsive to the supply of coded resetting energy over the section rails for supplying to the section rails at the entrance end thereof coded energy the polarity of which is governed by the second auxiliary relay for the adjacent track section in the rear.

12. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track divided into a plurality of track sections through which trafi'ic normally moves in a given direction, means for projecting coded detector energy of normal polarity away from the entrance end of the track stretch over the rails of the track section nearest the entrance end of the stretch, each section having at the exit end thereof a first auxiliary relay having a pick-up circuit which is established when and only when coded detector energy of normal polarity is supplied over the rails of the said section, each first auxiliary relay when picked up establishing for itself a stick circuit which is interrupted on supply of coded ener y of reverse polarity over the rails of the associated track section, each track section having at the exit end thereof a second auxiliary relay which is energized when the supply of coded detector energy over the rails of said section is out off provided the associated first auxiliary relay is picked up, each first auxiliary relay when energized causing to be supplied to the rails of the adjacent track section in advance coded detector energy of normal or reverse polarity according as the associated second auxiliary relay is picked up or released, means for each sectionresponsive to the supply of coded detector energy of either polarity over the section rails for supplying over the section rails towards the entrance end thereof coded control energy of normal or reverse polarity according as coded control energy is or is not being supplied over therails of the adjacent track section in advance, means responsive to coded control energy supplied over the rails of; said track sections and selectively responsive to the polarity of such energy for governing trafiic in said track stretch, means for each section operative when the first and second auxiliary relays for such section are picked up to supply coded resetting energy to the section rails at the exit end thereof, and means for each section responsive to the supply of coded resetting energy over the section rails for supplying to the section rails at the entrance end thereof coded energy the polarity of which is governed by the second auxiliary relay for the adjacent track section in the rear.

13. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track through which traflic normally moves in a selected direction, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections, means for each section governed by the supply of coded energy over the rails of the adjacent track section in the rear from the entrance to the exit end thereof for supplying coded energy to the section rails at the entrance end of the section, means for each section responsive to supply of coded energy over the section rails from the exit end of the section for also supplying coded energy to the section rails at the entrance end thereof, means for each section responsive to the supply of coded energy over the section rails from the entrance end thereof for supplying coded energy to the section rails at the exit end thereof, means for each section efiective during occupancy thereof for also supplying coded energy to the section rails at the exit end of the section, and means governed by coded energy supplied over the rails of said sections from the exit to the entrance end thereof for controlling traffic in said stretch.

14. In a normally deenerglzed coded railway signaling system, in combination, a stretch of railway track through which trafl'lc normally moves in a selected direction, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections, means for each section governed by the supply of coded energy over the rails of the adjacent track section in the rear from the entrance to the exit end thereof forsupplying coded energy to the section rails at the entranceend of the section, means for each'section responsive to supply of coded energy over-the: section rails from the exit end of the section for also supplying coded energy to the section rails at the entrance end thereof, means for each section responsive to the supplyof coded energy over the section rails from the entrance end thereof for supplying coded energy to, the section rails at the exit end thereof, meansfor each section effective during occupancy thereof for also supplying coded energy to the section .rails at the exit end of the section, and'traffie governing .means for each section controlled by. coded energy supplied over the rails of the adjacent section in advance from the exit to the entranceend thereof.

15. In a normallydeenergized coded railway signaling systemg ini combination, a stretch of railway track through which traffic normally moves in a given direction, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections, each section having at the entrance end thereof a normally released auxiliary relay which becomes picked up when and only when coded energy of a first type is supplied over the, rails of the adjacent section in the rear from the entrance to the exit end thereof and which when picked up remains picked up until coded energy of aseco'n'd type is supplied over the rails of the adjacent section in-the rear from the entrance to the exit end thereof, each auxiliary relay when picked up causing coded energy to be supplied to the rails of the associated section at the entrance end thereof, means for each section responsive to the supply of coded energy over the section rails from the exit end thereof for also supplying coded energy to the section rails at the entrance end thereof, means for each section for causing the coded energy supplied to the section rails at the entrance end thereof to be of said first or said second'typ'e according as the adjacent section in the rear is occupied or is unoccupied, means for each section responsive to the supply of coded energy over the section rails from the entrance end thereof to supply coded energy to the section rails at the exit end of the section, means for 'each section controlled by the auxiliary relay of the adjacent section in advance for also supplying coded energy to the section rails at the exit end thereof, each set:-

. tion having a wayside signal at the entrance end thereof, and means for each section responsive to the supply of coded energy over the section rails from the exit end thereof for controlling the signal for the section.

16-. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track through which trailic normally moves in a given direction, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections, each section'having at the entrance end thereof a normally released auxiliary relay which becomes picked up when and omy when codedenergy of a first type is supplied over the rails of the adjacent section in the rear from the entrance to the exit end thereof and which when picked up remains picked up until coded energy of a second type is supplied over the rails of the adjacent section in the rear from the entrance to the exit end thereof, each auxiliary relay when picked up causing coded energy to be supplied to the rails of the associated section at the entrance end thereoflmeans for each section resp'ons'ive to the'slupply of codedienergy over the section rails from the exit end thereof for also supplying coded energy to the section rails at the entrance end thereof, means for each section for causing the coded energy supplied to the section rails at the entrance end thereof to be of said firstor said second type according as the adjacent section in" the rear is occupied or is unoccupied, means for each section responsive to the supply of coded energy over the section rails frorn the entrance end thereof to supply coded energy to the section rails at the exit end of the section, means for each section controlled by the auxiliary; relay of the adjacent section in advance .forxalso supplying codedenergy'to the section fails at the exit end thereof, each ing the lamp of each signal only when the auxiliary relay of the section with which the signal is associated is picked up, and means for each section responsive to the supply of coded energy over the section rails from the exit end thereof for controlling the signal for the section.

17. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track through which traffic normally moves in a given direction, the rail of said track stretch being divided by insulated joints into a plurality of successive track sections, each section having at the entrance end thereof a normally released auxiliary relay which becomes picked up when and only when coded energy of a first type is supplied over the rails of the adjacent section in the rear from the entrance to the exit end thereof and which when picked up remains picked up until coded energy of a sec ond type is supplied over the rails of the adjacent section in the rear from the entrance to the exit end thereof, each auxiliary relay when picked up causing coded energy to be supplied to the rails of the associated section at the entrance end thereof, means for each section responsive to the supply of coded energy over the section rails from the exit end thereof for also supplying coded energy to the section rails at the entrance end thereof, means for each section for causin the coded energy supplied to the section rails at the entrance end thereof to be of said first or said second type according as the adjacent section in the rear is occupied or is unoccupied, means for each section responsive to the supply of coded energy over the section rails from the entrance end thereof for supplying to the section rails at the exit end thereof coded energy which is of a first or a second type according as coded energy is or is not being supplied over the rails of the adjacent section in advance, means for each section controlled by the auxiliary relay of the adjacent section in advance for also supplying coded energy to the section rails at the exit end thereof, each section having a wayside signal at the entrance end thereof, and means for each section controlled by coded energy supplied over the section rails from the exit end thereof and selectively responsive to the type of such energy for controlling the signal for the section.

18. In a normally deenergized coded railway signaling system, in combination, a stretch of railway track through which traific normally moves in a given direction, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections, each section having at the entrance end thereof a first, a second and a third normally released auxiliary relay, each first auxiliary relay being picked up on the supply of coded energy over the rails of the adjacent section in the rear from the entrance end thereof provided the associated third auxiliary relay is released, each second auxiliary relay being picked up when the supply of coded energy over the rails of the adjacent section in the rear is cut off and the associated first auxiliary relay is picked up, each second auxiliary relay when picked up remaining picked up as long as the associated third auxiliary relay remains released, each third auxiliary relay being picked up on the supply of coded energy over the rails of the adjacent section in the rear provided the associated second auxiliary relay is picked up, each second auxiliary relay when picked up causing coded energy to be supplied to the rails of the associated section at the entrance end thereof and also causing to be supplied to the rails of the adjacent section in the rear at th exit end thereof coded energy which is of a first or a second type according as coded energy is or is not being supplied over the rails of the associated section from the exit end thereof, means for each section responsive to the supply of coded energy over the section rails from the exit end thereof for also causing coded energy to be supplied to the section rails at the entrance end thereof, means for each section responsive to the supply of coded energy over the section rails from the entrance end thereof for also causing coded energy to be supplied to the section rails at the exit end thereof, and traflic governing means for each section responsive to the type of coded energy supplied to the section rails at the exit end of the section.

19. In a normally deenergized coded railway signaling system, incombination, a stretch of railway track through which are operated in a given direction locomotives equipped with cab signal apparatus responsive to the flow of coded alternating current in the track rails, the rails of said track stretch being divided by insulated joints into a plurality of successive track sections, each section having at the entrance end thereof a first, a second and a third normally released auxiliary relay, each first auxiliary relay being picked up on the supply of coded energy over the rails of the adjacent section in the rear from the entrance end thereof provided the associated third auxiliary relay is released, each second auxiliary relay being picked up when the supply of coded energy over the rails of the adjacent section in the rear is cut off and the associated first auxiliary relay is picked up, each second auxiliary relay when picked up remaining picked up as long as the associated third auxiliary relay remains released, each third auxiliary relay being picked up on the supply of coded energy over the rails of the adjacent section in the rear provided the associated second auxiliary relay is picked up, each second auxiliary relay when picked up causing coded direct current energy to be supplied to the rails of the associated section at the entrance end thereof and also causing to be supplied to the rails of the adjacent section in the rear at the exit end thereof coded alternating and direct current which is of a first or a second code frequency according as coded energy is or is not being supplied over the rails of the associated section from the exit end thereof, means for each section responsive to the supply of coded direct current over the section rails from the exit end thereof for also causing coded energy to be supplied to the section rails at the entrance end thereof, and means for each section responsive to the supply of coded energy over the section rails from the entrance end thereof for also causing coded direct current to be supplied to the section rails at'the exit end thereof.

ARTHUR L. JEROME. 

